When a personal computer is turned on, a basic input-output system (“BIOS”) that is stored in non-volatile solid state memory of the computer is invoked to begin what is known as a “boot” process, in which various initialization chores are undertaken. Among the most important of these chores is the copying of a user operating system (UOS) from disk storage of the computer over into a solid state memory of the computer, for execution of the UOS by the processor of the computer when the computer is being used. When the computer is turned off or when it is “re-booted”, the UOS is flushed from the memory.
Once booted and running, a UOS may cause its computer to enter a so-called “low power” mode after a period of inactivity to conserve energy. Part of a “low power” mode may be to place various devices of the computer such as, e.g., a wireless transmitter, a computer monitor, a printer, a hard disk drive (HDD), etc. in reduced energy consumption modes. To do this, a UOS may access a data structure known as an “advanced configuration and power interface” (ACPI) table, which lists devices that might be candidates for low power mode operation, to enable the UOS to execute certain codes in BIOS to deenergize appropriate devices.
As understood herein, “virtual machine monitors” (VMM) have been introduced that are essentially supervisory operating systems operating in the background to coordinate, among other things, the simultaneous operation by a single processor of both a main UOS and a service operating system (SOS). As further understood herein, this feature of VMM use introduces a new problem, namely, the unwitting deenergization of a device, by the UOS pursuant to low power mode operation, that the SOS or indeed VMM itself may require.